Ice machines include an evaporator assembly that includes a refrigerant conduit and an evaporator pan. The evaporator pan has a front side upon which ice cubes are formed and a back side that is in thermal transfer relation to the refrigerant conduit. The refrigerant conduit is constructed of copper tube formed into a serpentine shape. The copper tube sections are circular in cross-section, which provides a non-uniform refrigerant flow spacing from the back of the evaporator pan, thereby resulting in a non-uniform heat transfer across the diameter of the copper tube. Moreover, adjacent tube sections are spaced so much from one another that the refrigerant flow covers a relatively small area of the back of the evaporator pan, which typically is about 25% or less.
The ice assemblies are generally formed by soldering the copper tube serpentine to the back of the evaporator pan opposite the side of the ice forming structures. Each solder area is an area of structural weakness that can fracture during operation. Also, the multiple solder areas increase the cost and time of assembly.
There is a need for an evaporator assembly with an improved heat transfer and for a method of making the evaporator assembly.
The present invention allows for two evaporator pans and ice grids per serpentine. This increased refrigerant contact area and quantity of evaporator pans and ice grids lead to the following advantages:                1) Allows the ice machine to run at a higher evaporator temperature for a given ice capacity resulting in a 30% reduction in energy consumption.        2) The increased evaporator efficiency results in the ability to substantially reduce compressor size, resulting in lower costs and less noise.        3) For a given ice making capacity, evaporator internal volume is reduced by 65%, resulting in lower refrigerant costs and less compressor floodback during harvest.        4) For a given ice making capacity, evaporator weight is reduced by 65%. This reduces the amount of capacity and energy required to cool and heat the evaporator for the freeze and harvest cycles. This also reduces evaporator costs as less material is required.        5) The increased evaporator efficiency allows for a smaller evaporator for a given ice capacity resulting in smaller overall machine size.        6) Existing copper designs require a nickel plating to be compliant with National Sanitation Foundation (NSF) requirements. Stainless steel has no such plating requirement resulting in substantially lower evaporator costs.        7) Evaporator assembly 120 allows nearly 100% of evaporator pans 122 and 124 to be in direct contact with the refrigerant. Existing copper tube designs have 0% of the evaporator pans in direct contact with the refrigerant. Existing copper tube designs use a soldering process to attach a copper tube to a copper evaporator pan. The copper tube typically covers only 25% of the evaporator pan. Also, copper tube designs and manufacturing processes allow for only one evaporator pan and ice grid per serpentine.        